95 506 patients who received general anesthesia during the period of 1964--1977 were studied. The account of all actual or possible life threatening complications during the anesthesia is given: oedema of the glottis, air embolism, accidental injection of the wrong drug, respiratory insufficiency, hypoxia, pulmonary oedema, airway occlusion by the cuff, vomiting and aspiration, anaphylactoid reaction, death within 24 hours, death on the table. Deaths not attributable to anaesthesia are listed separately. We have found that in one of every 139 anaesthetics given there was a life threatening complication to the patient. In every 197th anaesthetic there was a clear connection with the anaesthetic technique used. In contrast with the great number of near fatal complications the rate of irreversible damage or mortality connected with general anaesthesia was low.